push rod length question
 

putting together my 455 and want to make sure i am on the right path. i am using e heads with 7/16 arp studs. i have a set of 7/16 1.65 ratio roller rockers i plan on using. using johnson retro fit roller lifters on a comp roller cam. put the rocker arms on today and mocked up with a standard length push rod and discovered it only left about 2-3 threads on the stud for the rocker arm nut to catch on. [the lifter was on the cam base] i then installed my adjustable push rod and found if i went to a 9" long pushrod i gained a lot more threads for the rocker arm nut to catch. contact pattern looked pretty good. my question is if i use a 9" pushrod will it effect valve lift? i rolled the motor over several times with this set up and saw no clearance issues. i am just wanting to confirm this would work.

this is the standard length pushrod. notice only a couple of threads.
https://www.supermotors.net/getfile/...8-16.12.31.jpg
here is the contact area
https://www.supermotors.net/getfile/...8-16.12.56.jpg

this with my adjustable pushrod set at 9"
https://www.supermotors.net/getfile/...8-16.15.56.jpg
https://www.supermotors.net/getfile/...8-16.17.26.jpg
this is the contact pattern with a 9" pushrod

One would use shorter pushrods on a roller cam. I believe most end up around 8.800 to 8.900. Mine runs 8.900 with eddie heads and harland sharp 1.5`s.


Something to think about.

Not necessarily. Depends on valve length, base circles etc. I use a 9.100" pushrod. It's right for my application. Use whatever length gives the correct pattern on the valve stem, and the rocker nut should have proper engagement, assuming correct rocker studs.

The last photo has a very nice contact pattern. Every different lifter, rocker arm, and head will change the necessary length of the pushrod. A Johnson lifter has a different length than a Johnson Hy-lift than a Comp and so on.

As long as the nut has full thread contact thru it's core then it does not matter if there was even just one exposed thread showing above the nut.

Those are jam nuts your using your instead of polylocks?

You can always change out the studs for a bit longer. You just have to watch stud depth and the chamfer on the studs.
Good video to watch. https://www.youtube.com/watch?v=o5is9BsH5OU
Which Johnson lifter are you using?

If you get new studs check out the dimensions of this ARP 334-7203 stud on summit racing

I believe it's this stud that allowed full roller rocker body on unthreaded portion of stud and put the polyloc in the sweet spot as well for my e'head set up

Alot of mock up and simple measuring of 4 points of interest, penetration in head, length of unthreaded portion = best place for rocker fulcrum to reside, will polyloc go down far enough to give valve preload / adjustment, and finally set screw engagement flush to a little low or a little high

I am using the nuts that came with the rockers. They have a set screw. The pics shown have no nut on the stud. That is how many threads are exposed to run the nut down on.

from the pic...your stock length MAY be long. as stated above all lifter/head/rocker combos get different. NO length of push rod will not affect valve lift IF you have a descent tip pattern. Next you want to look under the rocker to verify spring keeper clearance. From your pics you will need either pushrods or taller studs? NOW given angles and rotational ARC of a rocker YES you could actually decrease valve lift but you would have to be WAY off to make any MINOR change in the actual valve lift. With your "poly locks" do understand that after you SNUG up the set screw then you tighten the NUT. ;)